Studs are a type of fastener with a threaded cylindrical barrel on one end of the fastener that mates with a complementary thread in a fixture. Commonly studs are removed by tightening two nuts together on the accessible threaded side of the stud, and then applying a counterclockwise rotational force to one of the nuts. This technique for stud removal is much more difficult for a stud that has been corroded or has been in the same place for some time. Studs that have been corroded or have been in place for some time are prone to breaking, and so there is a need for a removal tool for broken studs.
A further complication of using manual tools for large stud removal, such as studs used in oil production, is that manual removal of such damaged studs presents danger to the operator. Further, manual removal may be impossible because the degree of torque required is greater than the strength of the operator.
One type of device accomplishes removal by cutting the stud out of the fixture using a blow torch. However, this method of stud removal results in damage to the stud and the fixture. One solution is to use devices that either drill the stud, or cut into the stud, so that torque can be applied to the nut for removal. However, these devices also result in further stripping of the threads of the stud, impeding removal from the fixture.
Another type of device accomplishes fastener removal by inserting an electrode into the broken stud and using a series of intermittent electrical arcs to disintegrate the stud, leaving a stud casing which is then removed manually. Finally the threads of the fixture are cleaned. However, this method of removal results in damage to the stud, is time consuming, involves multiple steps for stud removal, and may result in damage to the fixture.
Other devices using an air impact tool for the removal of large studs exist. Such devices may require a cartridge having many small parts that is used to apply torque to the damaged stud. These multiple small parts of the cartridge, such as multiple helical springs, studs and screws holding gripping jaws together, are prone to breakage when the rotative force of an air impact tool is applied.
Another prior art stud removal tool consists of a housing having a cylindrical bore with finger splits on one end of the housing, and the other end of the housing connecting to an air impact tool. However, the finger splits of the housing cannot fit over multiple stud sizes, so that the tool is limited in usage.
A further complication of the cartridges and associated parts is the use of a retaining ring or clip. The retaining ring or clip is prone to breakage, resulting in a damaged and useless tool.
Another complication of stud removal is side loading, or the mechanical binding of threaded surfaces against each other. When side loading occurs, heat builds up due to friction between the threaded surfaces, creating a gall which is carried through the housing, tearing out the threads and impeding stud removal.
Yet another complication is “chattering,” where the tool does not perfectly conform to the size of the fastener. When rotative force is applied using an air impact tool, the removing tool “chatters” over the damaged corners of the fastener, further stripping the fastener or damaging the tool interface with the fastener, and causing ‘radii’ to form on the end of the tool.
The use of a set of tools having a multiplicity of sizes to conform to different stud sizes exists which proposes to solve the problem of imperfect conformance between removal tool and stud size. However, regardless of the size, the prior art nonetheless results in chattering from an imperfect size conformance; thus, stripping of the thread occurs.
Further, the use of a set of tools having a multiplicity of sizes to conform to stud size presents another complication. If there exists a multiplicity of removal tool sizes in a set, the loss of one of the tools results in a useless tool set.
It would thus be desirable to have a stud removal tool that conforms to the size and shape of a multiplicity of studs, where the jaws of the tool comprise one piece, rather than a multiplicity of smaller pieces which can be easily lost or damaged, and where the jaws are retained within the housing through a shock-absorbing canted coil spring.